Chorionic exposure to very low concentrations of the widely used anesthetic, halothane has been implicated by correlative studies in the human as deleterious to health and capability. In the rat we have found that 10 ppm of halothane in air during early gestation and nursing produces offspring which have enduring deficits in maze learning tasks, and flinch-jump thresholds as well as correlative CNS damage. We plan to determine if these effects are teratogenic, the sensitive period for their production, and their quantitative relationship to brain damage. The present studies will expand upon our neurobehavioral correlation by quantitative ultrastructural and behavioral measurements at various dosage levels of halothane administered from conception to 60 days of age (dose-response functions). At one of these selected halothane dosages, the studies will be then examine brain regional differences in ultrastructural and neurochemical effects. Finally, the studies will assess the effects of exposure to a selected halothane dosage in restricted time periods during early development, studying brain regions and behaviors which the prior experiments find to exhibit effects. These data, even though obtained on the rat, will be important in setting health safety standards for human exposure to halothane, or in identifying selected crucial areas for further research in the monkey (experimental) or human (correlational) necessary to the final determination of health safety standards. BIBLIOGRAPHIC REFERENCES: Quimby, K.L., Katz, J., and Bowman, R.E. Behavioral Consequences in Rats from Chronic Exposure to 10 PPM Halothane During Early Development. Anesthesia and Analgesia, Vol. 54, No. 5, 628-633, 1975.